Affinity Photo triangle brushes ? How To Create ? The vector shapes in the tools panel can all be used as a source for a brush, such as a the triangle tool. Use the control bar as well as the limited interactive settings to create a lovely vector design which can be thin or wide, short or tall. You can also angle the design. You can also fill it with different designs or just keep it a solid color like black. You can create multiple copies as well to create a more complex design. Or use it with opacity and blends and combine with other shapes. Or perhaps apply layer effects to the design such as bevels and shadows
It needs to be a raster to be used as a stroke, so it can't remain as a vector design. You can turn that it into a raster / pixel layer via the rasterize command in the layer menu. You will now see it in the layers panel as a pixel layer
Once converted, you can then goto the panel and right side menu and create brush from selection.
Once you have added that resource, they you can double click that resource / preset and edit it and change the size, spacing, hue jitter, saturation jitter, spacing and much more and create many unique strokes for use throughout the application